1. Feature Of The Week

    Shear wave measurements for the determination of tissue elastic properties have been used in clinical diagnosis and soft tissue assessment. A shear wave propagates as a transverse wave where vibration is perpendicular to the wave propagation direction. Using shear wave elastography, the shear modulus of a soft tissue can be quantified by tracking the shear wave propagation. In previous measurements, the transverse shear wave propagates perpendicular to the force direction, so the shear modulus in the lateral region of the force can be quantified. However, the shear modulus in the axial region of the force cannot be measured.

    Dr. Jiang Zhu, Yusi Miao and other researchers in Prof. Zhongping Chen’s group at the Beckman Laser Institute, the University of California Irvine, visualized a longitudinal shear wave using optical coherence tomography for the quantitative mapping of shear moduli. They demonstrated that a longitudinal shear wave propagated along the vibration direction as a plane wave in the near field of a planar source, and the shear modulus in the axial region of the force was quantified. Furthermore, combination of the transverse shear wave and the longitudinal shear wave provides opportunities for measuring directionally dependent elastic properties in tissues, such as muscles, tendons, etc.

    The utilization of the longitudinal shear wave provides good theoretical and practical insights. This is an important improvement to resolve the limited field of view in optical coherence elastography, and provides significant information for the clinical diagnosis of diseases.

    For more information see recent Article. Courtesy Jiang Zhu, from University of California at Irvine. To share this article click Here.

  2. Recent Articles From Around The Web

    1. Feature of The Week 05/19/2017: Longitudinal Shear Wave Imaging for Elasticity Mapping Using Optical Coherence Elastography

      Feature of The Week 05/19/2017: Longitudinal Shear Wave Imaging for Elasticity Mapping Using Optical Coherence Elastography

      Shear wave measurements for the determination of tissue elastic properties have been used in clinical diagnosis and soft tissue assessment. A shear wave propagates as a transverse wave where vibration is perpendicular to the wave propagation direction. Using shear wave elastography, the shear modulus of a soft tissue can be quantified by tracking the shear wave propagation. In previous measurements, the transverse shear wave propagates perpendicular to the force direction, so the shear modulus in the lateral region of the force can be quantified. However, the shear modulus in the axial region of the force cannot be measured. Dr. Jiang ...

      Read Full Article
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    3. Wide Broadband ASE Source based on Thulium-doped Fibre for 2 μm Wavelength Region

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      In this paper, we present a real-time instantaneous phase estimation technique for the calibration of swept source optical coherence tomography (SS-OCT) systems. The proposed algorithm is able to accurately estimate both the amplitude and phase content of a swept source signal. The results are robust in the presence of substantial noise. Furthermore, the resulting phase profile is readily unwrapped, allowing for the generation of a k-linear sampling clock by means of a simple comparison step, which enables the SS-OCT system operator to determine the required number of points for accurate image reconstruction without the need for MZI path length modification ...

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      Foveal Curvature and Asymmetry Assessed Using Optical Coherence Tomography

      Purpose: The aims of this study were to use cross-sectional optical coherence tomography imaging and custom curve fitting software to evaluate and model the foveal curvature as a spherical surface and to compare the radius of curvature in the horizontal and vertical meridians and test the sensitivity of this technique to anticipated meridional differences. Methods: Six 30-degree foveal-centered radial optical coherence tomography cross-section scans were acquired in the right eye of 20 clinically normal subjects. Cross sections were manually segmented, and custom curve fitting software was used to determine foveal pit radius of curvature using the central 500, 1000, and ...

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    8. Profound Macular Ischemia on Optical Coherence Tomography Angiography in Severe Diabetic Retinopathy

      Profound Macular Ischemia on Optical Coherence Tomography Angiography in Severe Diabetic Retinopathy

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      Mentions: Optovue
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      Re: Goto et al.: Prediction of postoperative intraocular lens position with angle-to-angle depth using anterior segment optical coherence tomography (Ophthalmology. 2016;123:2474-2480)

      To the Editor: We read with interest the study by Goto et al, 1 who described a new formula to predict the postoperative position of the intraocular lens (IOL). Although their results are interesting and might be useful for IOL power calculation, we feel that some comments are necessary. First, comparing what they define as the “postoperative external anterior chamber depth,” either measured or predicted by anterior segment optical coherence tomography, to the IOL position, as predicted by thin lens formulas, is not the proper method. The measurements performed by the authors, in fact, refer to a thick lens system ...

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      Mentions: Giacomo Savini
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      RE: Traber et al.: Enhanced depth imaging optical coherence tomography of optic nerve head drusen: a comparison of cases with and without visual field loss (Ophthalmology. 2017;124:66-73)

      To the Editor: We read with interest the study by Traber et al, where the presence or absence of visual field defects was correlated with optic nerve head drusen (ONHD) morphology. 1 The ONHD were classified using enhanced depth imaging optical coherence tomography (OCT) morphologic characteristics as either peripapillary, granular, or confluent. The hyperreflective structures classified as peripapillary ONHD in the present study have previously been labeled as ONHD 2 ; however, we do not find substantial evidence for this suggestion. First, we regularly see similar hyperreflective mass-like peripapillary changes in OCT volume scans of patients with papilledema from idiopathic intracranial ...

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    11. HS-UK to host Ophthalmic Ultrasound & OCT-A Course

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      Haag-Streit UK (HS-UK), the leading manufacturer and distributor of gold-standard optometry and ophthalmic equipment, is delighted to confirm that it will be hosting an Ophthalmic Ultrasound & OCT Course at Crewe Hall, Cheshire on Wednesday 28th June, 2017. The course is aimed at those working with ophthalmic ultrasound in their daily practice, and will cover both A-scans and B-scans, including how to capture them. Lectures will describe some of the common conditions observed using ultrasound, such as; retinal detachments & tears, vitreous haemorrhages & detachments and optic disc drusen & other dot lesions. The day will also include a lecture covering the detection of ...

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      Mentions: Haag-Streit
    12. Measurement of macular structure-function relationships using spectral domain-optical coherence ...

      Measurement of macular structure-function relationships using spectral domain-optical coherence ...

      Background Retinal ganglion cell (RGC) death is a common cause of loss of vision during glaucoma. Pattern electroretinogram (PERG) is an objective measure of the central retinal function that correlates with macular GCL thickness. The aim of this study is to determine possible relationships between the N95 amplitude of pattern electroretinogram (PERG amp ) and macular ganglion cell/inner plexiform layer thickness (GCIPLT). Methods and findings This was a retrospective and comparative study including 74 glaucoma patients (44 early stage and 30 advanced stage cases) and 66 normal control subjects. Macular GCIPLT was measured using Cirrus spectral domain-optical coherence tomography. Standard ...

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    13. Spontaneous Coronary Artery Dissection: Insights From Histology and Optical Coherence Tomography

      Spontaneous Coronary Artery Dissection: Insights From Histology and Optical Coherence Tomography

      Spontaneous coronary artery dissection (SCAD) is a well-known but infrequent cause of acute coronary syndrome (ACS), and often goes unrecognized. Although management of SCAD is, at times, controversial, when a patient presents with ACS, percutaneous coronary intervention (PCI) is frequently necessary. We present a patient with ST-segment elevation myocardial infarction (STEMI) with SCAD that illustrates two important points: use of intracoronary optical coherence tomography to guide PCI, and histologic assessment to provide a unique insight into the etiology of SCAD. Following the case, we briefly review the important aspects of the pathophysiology, epidemiology, diagnosis, and interventional management of SCAD.

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    14. Development and translation of label-free functional microscopy based on optical coherence tomography (Thesis)

      Development and translation of label-free functional microscopy based on optical coherence tomography (Thesis)

      Optical coherence tomography (OCT), an imaging modality based on low coherence interferometry, can be extended to obtain various endogenous functional contrasts. This thesis focuses on the development and translation of angiographic and polarization sensitive (PS) OCT techniques for clinical and preclinical applications. This goal includes four specific aims. The first aim is to develop a clinical imaging system to image the anatomy and microvasculature of human skin. The second aim is to develop a high performance post-processing algorithm for angiographic OCT. Towards this aim, we developed a processing algorithm based on complex differential variance (CDV) and confirmed its performance by ...

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    15. THREE-DIMENSIONAL ANALYSIS OF SUBMACULAR PERFORATING SCLERAL VESSELS BY ENHANCED DEPTH IMAGING OPTICAL COHERENCE TOMOGRAPHY

      THREE-DIMENSIONAL ANALYSIS OF SUBMACULAR PERFORATING SCLERAL VESSELS BY ENHANCED DEPTH IMAGING OPTICAL COHERENCE TOMOGRAPHY

      Purpose: To analyze submacular perforating scleral vessels (PSVs) using enhanced depth imaging spectral domain optical coherence tomography (EDI-SDOCT). Methods: Twenty-two eyes of 11 healthy women were included in this retrospective study. Central EDI-SDOCT scans (3 x 4.5 x 1.9 mm, 13.5 mm2 scan area) were acquired and postprocessed by denoising, manual sclera segmentation, and PSV investigated by five graders. Results: Mean age was 22.4 +/- 6.2 years. Mean refractive error was -0.44 +/- 0.8 diopters. Mean axial length was 23.08 +/- 0.63 mm. The coefficient of agreement for grading was good. Mean number of ...

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    16. See all articles
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    1. (2 articles) Jiang Zhu
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  5. Picture Gallery

    Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography Faculty Position  at Geisinger Medical Center Conical scan pattern for enhanced visualization of the human cornea using polarization-sensitive OCT PhD Student Position in integration of a micromachined endomicroscope for OCT imaging in gastroenterology New Endoscope to Enable Faster, More Accurate Colorectal Cancer Diagnosis NinePoint Medical to Feature the NvisionVLE® Imaging System with Real-time Targeting™ at DDW 2017; Twenty-four Scientific Abstracts to be Presented Damae Medical Raises €2M in Funding Endothelial progenitor cells and plaque burden in stented coronary artery segments: an optical coherence tomography study six months after elective PCI Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection Finalists for the European Inventor Award 2017 Feature of The Week 05/19/2017: Longitudinal Shear Wave Imaging for Elasticity Mapping Using Optical Coherence Elastography Optical coherence tomography findings: insights from the “randomised multicentre trial investigating angiographic outcomes of hybrid sirolimus-eluting stents with biodegradable polymer compared with everolimus-eluting stents with durable polymer in chroni
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